Unlike TCP,
UDP provides best effort communications for its data
delivery, and that's okay because without it,
important services such as voice and video conferencing couldn't
operate. Without UDP, even your online games would fail.
And that means no more Halo 3 multiplayer. Yikes!
Let's take a few minutes to take a closer look at
the best‑effort protocol of UDP.
UDP is known for the delivery mechanism of best effort.
The easiest way to think of best effort is through a cell phone call.
Have you ever been driving your car and hit a low‑service area,
but then instantly your call is restored. During the low‑service
area, you may have missed a few words here and there,
but the conversation can continue to flow.
This is best effort.
Oftentimes engineers will incorrectly call this the unreliable protocol,
but this really isn't a fair embodiment of this protocol.
This protocol isn't unreliable.
It's just that if all the messages don't arrive,
that's okay, whereas something that is unreliable is like the car that
we've all owned at one point in time or another that only started about
half the time. UDP is also a lightweight protocol,
meaning it doesn't have as much overhead as TCP. Now, let's take a moment to
complete a high‑level overview of the UDP packet to help prep us for the module,
TCP and UDP Theory of Operation. UDP is a lighter protocol due to the header
being much smaller in size compared to TCP.
In this packet analysis,
we can see a computer searching for a DHCP server quite aggressively through
packets numbers 3 through 66. And in packets 73 through 75, we can see that a
server with the IP address of 192.168.1.254 gave the requesting PC an IP
address of 192.168.1.100. And just to be sure,
let's verify our DHCP lease on the server of 192.168.1.254. Great! It looks like
Wireshark was correct in supporting of the network traffic.
If a lot of the information presented here doesn't make sense,
that's okay because just like TCP, we'll be decomposing
UDP in the modules, TCP and UDP Theory of Operation and
TCP and UDP Ready Set Action, at which point you'll have a solid understanding of UDP.